This study presents the experimental results of the effects on base oils after thermal and electrical aging to determine key parameters of next-generation fluids for thermal management in electric vehicles. The test fluids selected were a mineral base oil API G-III, an API G-IV Polyalphaolefin (PAO), a diester, and a polyolester, all of which had similar kinematic viscosity (KV100 = 4 cSt). All were initially characterized with measurements of density, viscosity, thermal conductivity, specific heat capacity, breakdown voltage, resistivity, and dissipation factor. They underwent two separate aging processes, one thermal, heating the test fluid at 150 °C for 120 h with a copper strip as a catalyst; and the second one an electrical aging process, with the application of 1000 breakdown voltage discharges. The same properties were measured again after each aging process and compared to the initial ones. It was found that the thermal properties ranged with similar values and did not suffer major changes after the aging processes, unlike electrical properties, which vary between samples and after thermal and electrical stress. The insights gained from this study have implications for both the development of next-generation e-thermal fluids and the future standardization of these fluids for EV thermal management applications. The findings of this study underscore the significance of formulating and selecting a suitable dielectric fluid for EV thermal management. By leveraging the insights provided, researchers and engineers can advance in the development of efficient and reliable e-thermal fluids while working towards future standardization to enhance the performance and safety of EV battery systems.

Wall-flow particulate filters are a required exhaust aftertreatment system to abate particulate matter emissions and meet current and incoming regulations applying worldwide to new generations of diesel and gasoline internal combustion engines. Despite the high filtration efficiency covering the whole range of emitted particle sizes, the porous substrate constitutes a flow restriction especially relevant as particulate matter, both soot and ash, is collected. The dependence of the resulting pressure drop, and hence the fuel consumption penalty, on the particulate matter distribution along the inlet channels is discussed in this paper taking as reference experimental data obtained in water injection tests before the particulate filter. This technique is demonstrated to reduce the particulate filter pressure drop without negative effects on filtration performance. In order to justify these experimental data, the characteristics of the particulate layer are diagnosed applying modeling techniques. Different soot mass distributions along the inlet channels are analyzed combined with porosity change to assess the new properties after water injection. Their influence on the subsequent soot loading process and regeneration is assessed. The results evidence the main mechanisms of the water injection at the filter inlet to reduce pressure drop and boost the interest for control strategies able to force the re-entrainment of most of the particulate matter towards the inlet channels’ end.

According to current worldwide trends for homologation vehicles in real driving conditions is forced to test the engines in altitude and in highly dynamic driving cycles in order to approach nowadays and next future emissions standard. Up to now, there were two main options to perform this type of tests: round-robin tests of the whole vehicle or hypobaric chambers, both with high costs and low repeatability. In this paper a new device is described, which can emulate ambient conditions at whatever altitude between sea level and 5000 m high. Even it can be used to emulate ambient conditions at sea level when test bench is placed up to 2000 m high. The main advantages of the altitude simulation equipment are as follows: dynamic emulation of all the psychrometric variables affecting the vehicles during round-robin tests; lower space usage and low-energy consumption. The altitude simulator (AS) has been validated comparing with results from a hypobaric chamber at different altitudes. Previously a research about the dispersion in the measurements of both testing devices has been done for assessing the results of the comparison experiment. Final conclusion resulted in the same operating performance and emissions of the studied engine with both types of testing equipment for altitude simulation.

Control strategies such as variations in injection pressure and timing have been used by researchers to reduce in-cylinder exhaust emissions and meet legislation standards. Postinjection has been studied for several years and is now well known as an efficient strategy for reducing soot emission. Diesel gaseous and particle mass emissions have been progressively reduced over the last twenty years as a consequence of increasingly restrictive emission legislation and the application of aftertreatment devices. The main objective of this work is to better understand the effect of postinjection on particle size distribution in diesel exhaust. The approach uses a modern, well-instrumented research engine test cell equipped with a flexible high pressure fuel injection system. The results of this work provide guidelines for developing strategies to reduce particle size distribution in diesel engines. A major improvement in particle size distribution was found in the accumulation mode by using a close postinjection of a small quantity of fuel. For reduction in nucleation mode, a relationship was found with close postinjections of large quantities of fuel.

This study explored the crucial relationship between base fluids and polyamide, a prevalent polymer in electric vehicle (EV) components, with the aim of enhancing the longevity and performance of EVs in the context of thermal management by immersion cooling. Focusing on polyalphaolefin and polyol ester as base fluids, an immersion test was conducted to assess their interaction with polyamide 6 using adapted ASTM standards. The results revealed the significant influences of both fluids on the physical properties and chemical structure of polyamide. Polyol ester demonstrated a lesser impact on the chemical and mechanical properties of polyamide 6.